Flag-transitive L_h.L*-geometries

The classification of finite flag-transitive linear spaces, obtained by Buekenhout, Delandtsheer, Doyen, Kleidman, Liebeck and Saxl [20] at the end of the eighties, gave new impulse to the program of classifying various classes of locally finite flag-transitive geometries belonging to diagrams obtained from a Coxeter diagram by putting a label L or L ∗ on some (possibly, all) of the singlebond strokes for projective planes

The universal covers of the sporadic semibiplanes

AbstractWe determine the universal covers of the few flag-transitive sporadic semibiplanes. They were already known by computer-aided coset enumeration. The method we are using seems to be new and of interest on its own